OP0271 INCIDENCE OF PSORIATIC ARTHRITIS AND PREVALENCE OF UNDIAGNOSED CASES IN A UK PRIMARY CARE POPULATION FOLLOWED PROSPECTIVELY FOR 2 YEARS - RESULTS FROM THE TUDOR RANDOMIZED CLINICAL TRIAL
Authors: N. Mchugh, L. Bojke, L. Coates, C. Davies, P. Helliwell, J. Packham, M. Ransom, E. Spackman, W. Tillett, S. Brown
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The incidence of psoriatic arthritis (PsA) in a psoriasis population has been reported to be somewhere between 20 to 300 per 10,000 person years (p-yrs) (1,2), the wide range reflecting differences in the population setting and the methods of ascertaining a diagnosis. A higher incidence is generally found in studies combining active screening and physical examination. However, accurate estimates of incidence and prevalence of undiagnosed disease are needed to inform the timing and cost-effectiveness of community screening in a general population with psoriasis. <h3>Objectives</h3> To determine the annual incidence of PsA in a UK primary care population with pre-existing psoriasis over two years after excluding baseline prevalence of existing and undiagnosed disease. <h3>Methods</h3> TUDOR (Total bUrDen of psORiasis) was a multi-centre, prospective, two-arm parallel-group cluster randomised controlled trial of the early identification of PsA by annual rheumatological assessment (termed Early Surveillance (ES) arm) versus standard care (SC) arm in people with psoriasis identified in primary care. Participants in the ES arm were recruited from primary care records held in 72 participating practices, invited to attend for a health check that included a screening examination for psoriatic arthritis and if the screen was positive their general practitioner was requested to refer them to the local rheumatology service to confirm a final diagnosis of PsA. The incidence reported here is from the ES arm, excludes prevalent cases of PsA identified at baseline and reports incidence at follow-up visits at 12 and 24 months. <h3>Results</h3> In the ES arm, 64 of 826 participants (7.7% (95% CI: 5.9, 9.6)) had a diagnosis of PsA, of whom 43 of 793 were diagnosed from the initial screening visit, corresponding to a prevalence of undiagnosed PsA at baseline of 5.4% (95% CI: 3.8, 7.0). Fourteen of 511 participants attending a 12-month screen developed PsA over that interval giving an incidence of 274 per 10,000 p-yrs (95% CI: 132 to 416 per 10,000 p-yrs) and another 7 of 444 participants attending the 24-month visit developed PsA giving an incidence of 158 per 10,000 p-yrs (95% CI: 42 to 274 per 10,000 p-yrs). The combined incidence over 2 years was 220 per 10,000 p-yrs (95% CI: 127 to 313 per 10,000 p-yrs). <h3>Conclusion</h3> In the ES arm of TUDOR where participants with psoriasis were screened and examined for the presence of PsA at baseline, 12 months and 24 months, the estimated cumulative incidence of PsA over a 2 year period was 220 per 10,000 p-yrs, that is in keeping with a higher incidence of PsA than that found when relying on health records alone. The long term clinical and cost-effectiveness of screening from the TUDOR trial remains under investigation. <h3>References</h3> [1]Wilson et al Arthritis Rheum 2009 Vol. 61; 233-239 [2]Eder et al Arthritis Rheum 2016 Vol. 68; 915-923 <h3>Acknowledgements</h3> This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme. <h3>Disclosure of Interests</h3> None Declared.